The Republican. [volume] (Oakland, Md.) 1877-current, 1887-04-02
COLLIERY EXPLOSIONS.
Efforts Which Have Been Made
to Prevent Them.
The "Davy' Lamp and Fire Damp-CoaI
Dust Dangers-''Shot-F Firing to Give
Place to Safer Methods of
Explosions.

The atmosphere of every coal-mine
probably contains more or less marsh
gas, although in some the amount is so
very small that the air within them
could never become explosive under or
binary conditions of working There
is no doubt that gas frequently escapes
detection owing to the imperfection of
the means employed for its recognition.
If present in certain proportions the
marsh gas is revealed by the elonca-
ton of the flame of the safety-lamp, or
by the appearance of what is
known as ''cap" upon the flame.
An experienced eye can determine pref
ty accurately the relative amount of
the fire-damp from the size and character
of the cap upon Il properly trimmed
flame; but the test altogether fails when
the proportion of gas falls below two
per cent. This amount, small as it may
seem, may, under certain circum-
stances, prove highly dangerous. The
mine-manager and the "fremen" re-
quire to use some more delicate method
of detecting small quantities of fire
damp than that usually employed. For
tunately such methods are notunknown.
Mr.. Liveing has devised very ingeni-
Gus indicator, by which the existence
of marsh gas can be detected and its
amount estimated even when the guam
tity is as low as a quarter per cent.
Two precisely similar pieces of thin
platinum wire are simultaneously
heated to bright redness by the action
of a small magueto-electric machine
worked by hand. One of the wires is
contained in a small tube filled with pure
air; the other can be surrounded at will,
and in a minute or two, with air
from any part of the mine. If fire.
damp is present it burns round the hot
wire, which is thereby increased in
temperature and emits a more brilliant
light. By comparing the intensities of
the light emitted by the two wires by
the aid of a very simple photometric
arrangement the percentage amount of
fire-damp present may be at once de-
termined. The apparatus is portable
and easily worked, and is well adapted
for use under ground.
Seventy years have elapsed since Sir
Humphrey Davy invented the safety
lamp which is associated with his name.
1t is almost impossible to overestimate
the influence of that invention in the
development of cOal-mining the de-
velopment, indeed, of our national
prosperity. 1t has unquestionably
saved thousands Of lives, and has en-
abled millions of tons of coal to be
raised which, without it, could not pos
sibly have been won.
1t is related that when Mr. Buddle,
whose name is well known in the
history of coal-mining for the
improvements he introduced into
the system of ventilating collieries,
took down one of the first Davy lamps
into fiery pit and beheld the fre-damp
leap" playing round the light and APP
parently imprisoned within the wire
gauze cylinder, he exclaimed exult-
ingly; AT last we have subdued this
monsterr'
Not a year passes, however, without
the monster showing us that he is
still very far from subiection; and,
strange to say, the Davy lamp itself
and the very system of ventilation
which we owe to Mr.. Buddle, as de-
veloped in these later times, have con-
spired to aid the monster in his work
of havoc and disaster.
How this has come about NAV be
told in very few words. When the
lamp was first introduced the ventilat-
ing currents in mines seldom exceeded a
velocity Of three hundred feet per
minute in the air-ways, and they were
usually very feeble in the working
places. Nowadays the enormous fans
and other mechanical ventilators which
are employed cause the air to travel at
velocities approaching two thousand
feet per minute in the anyways, and cur
rents of more than four hundred feet per
minute are not unfrequently met with
at the working places. Under these
conditions the Davy lamp and, in a
lesser degree, two other well-known
forms Of safety lamp--the Clanny and
the Stephenson lamps-become abso-
lutely unsafe in an explosive atmos-
phere. Indeed, the ordinary Davy
lamp will ignite gas outside it if ex-
posed to an explosive current travelling
at less than four hundred feet per min.
ute
The Royal Commissioners, as far back
as 1880, directed the attention of the
Home Secretary to the fact "that the